1. Field of the Invention
The invention relates to a process for the synthesis of 2-furylketones.
2. Description of the Related Art
Biological fouling, or biofouling, is defined as the unwanted buildup of microorganisms, plants, and animals on artificial surfaces. Marine biofouling is the undesirable accumulation of organisms on any artificial surface that is submerged in seawater, such as ship hulls, seaside piers, sea defenses, or any other surface that is continuously in contact with seawater. Biofouling of naval vessels causes an increase in surface roughness and higher frictional resistance. A slime layer as little as 1 mm in thickness can result in a 15% decline in ship speed (hydrodynamic drag). Increased drag of a vessel will result in higher operational costs, such as increased fuel consumption and decreased maneuverability.
Current antifoulant technologies have been found to be both harmful to marine life and to the environment. Presently, the most popular antifouling agents used in marine coatings worldwide are organotin compounds, namely tri-butyltin oxide (TBTO). Environmental concerns like these have pushed the EPA to investigate the effects of organotin antifoulants and as a result the International Maritime Organization (IMO) in October 2001 banned their use in marine paints as of Jan. 1, 2003. As a result, there is now an urgent need for new antifoulant technology that both effectively prevents organism growth and is environmentally friendly.
Naturally occurring antifoulant compounds are only available in limited amounts and often their structural complexity makes synthetic production in large quantities difficult. One analog of a naturally occurring antimicrobial agent, 2-furyl-n-pentylketone, has been a popular synthetic target. The majority of past synthetic strategies have involved Friedel-Crafts acylation chemistry and often resulted in poor yields and were rarely applied to large-scale preparations and/or involved the use of complex, expensive reagents. The various Friedel-Crafts acylation methods used to prepare 2-furyl-n-pentylketone have employed furan and an acid chloride or anhydride with a range of acid catalysts. Other groups have prepared 2-furyl-n-pentylketone by way of a facilitated acylation reaction between boronic acids and anhydrides in the presence of a palladium catalyst. Some groups have employed oxidative strategies of an α-hydroxyl furan that have proven difficult to carry out and the resulting ketone products often required chromatographic purification, which is troublesome for larger scale preparations. Alternative methods employed to prepare 2-furyl-n-pentylketone have involved an alkylation scheme usually involving either an acid chloride or furfural with the appropriate Grignard reagent. Alkylation in the case of furfural then required oxidation to afford the desired ketone product. Alternatively, 2-furyl-n-pentylketone may be prepared by way of the hydroacylation of 1-pentene with furfural in the presence of cocatalyst Wilkinson complex and 2-amino-3-picoline.